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Stropharia rugosoannulata

[ Basidiomycetes > Agaricales > Strophariaceae > Stropharia . . . ]

by Michael Kuo

This beautiful mushroom is easily recognized by its preference for wood chips and other urban habitats, its purple-gray gills and spore print, and its distinctive ring, which is thick, finely lined on the upper side, and radially split or "cogwheeled" on the underside. Fresh caps are wine red to reddish brown, but they often fade to yellowish brown.

I was searching rather fruitlessly for morels in Pennsylvania when a woman, out for a walk on the woodchip trail that borders my morel spot, asked what I was looking for. When I said "mushrooms," she replied, "What's wrong with these over here?" Stropharia rugosoannulata wasn't exactly what I had in mind that day, but the large clusters of mushrooms were, I had to admit, impressive. According to mushroom author Gary Lincoff (1992), this species "can be gathered week after week on compost or wood chips, where it produces hundreds of large, firm, fleshy mushrooms" (730). David Arora (1986) speculates that the species may be an "alien" to North America, since it grows in planted areas (379).

Moments later a troop of girl scouts came marching down the trail (I'm not making this up), shepherded by a very stern woman who lectured them about how fragile the forest ecosystem was, and how they should never stray from the trail or tromp around on things. There were many disapproving looks in my direction, though I tried to slip behind a large tulip poplar. As the troop faded away in a haze of woodchip-directed backpacks, cell phones, and giggles, I was left to wonder whether my mushroom collecting could be as invasive as plowing up miles of trails through the woods and covering them with non-native woodchips (and all their attendant mycelia and microbes)--and to wonder why my students hate walking in the woods . . .


Ecology: Saprobic, growing scattered or gregariously (sometimes in clusters) on woodchips, in gardens, and in other cultivated areas; spring through fall; widely distributed in North America.

Cap: 4-15 cm; convex or broadly bell-shaped at first, becoming broadly convex to flat; sticky when fresh, or dry; smooth; wine red to reddish brown, fading to tan or paler; sometimes developing cracks in old age; the margin sometimes hung with partial veil remnants.

Gills: Attached to the stem; whitish to pale gray at first, later purplish gray to purple-black; close.

Stem: 7-15 cm long; 1-3 cm thick; dry; equal, or with an enlarged base; smooth or fibrous; white, discoloring yellowish to brownish in age; with a thick ring that is finely grooved on its upper surface (and often blackened by spores) and radially split or "cogwheeled" on its underside; base with white mycelial threads.

Flesh: Substantial and white throughout; firm.

Odor and Taste: Pleasant.

Spore Print: Dark purple-brown to blackish.

Chemical Reactions: KOH on cap surface olive green.

Microscopic Features: Spores 10-14 x 6-9 µ; smooth; broadly elliptical. Chrysocystidia present.

REFERENCES: Farlow ex Murrill, 1922. (Stamets, 1978; Smith, Smith & Weber. 1979; Arora, 1986; Phillips, 1991/2005; Lincoff, 1992; Roody, 2003; Stamets, 2005; McNeil, 2006; Miller & Miller, 2006; Kuo, 2007.) Herb. Kuo 05080306, 08300403, 06300701.

Further Online Information:

Stropharia rugosoannulata at Roger's Mushrooms


Stropharia rugosoannulata

Stropharia rugosoannulata

Stropharia rugosoannulata

Stropharia rugosoannulata

Stropharia rugosoannulata

Albino Form

Stropharia rugosoannulata

Albino forms of Stropharia rugosoannulata are apparently not uncommon (see Phillips, 1991/2005). The collection above was made in woodchips, in Illinois. Aside from the white colors, other differences from the typical form included a strong creosote-like odor and a yellow (rather than olive) KOH reaction. Microscopic features were identical to those of the typical pigmented form.

An Odd Collection

Stropharia rugosoannulata

The mushrooms above were collected in Illinois. Aside from being a little bit more slender in stature than the typical form, they differed in their habitat: they grew from wood and leaf debris in a woodland flood plain. The debris had been left stranded in the previous spring. Evidently the creek, during spring floods, picked up some wood chips, garden mulch, or sod from a "typical" Stropharia rugosoannulata location upstream, and carried the mushroom's mycelium with it. A similar collection was made by Ron Kerner in Indiana.

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Kuo, M. (2007, October). Stropharia rugosoannulata. Retrieved from the MushroomExpert.Com Web site: